Method of bonding polyethylene to vulcanized rubber and article produced thereby



April 21, 1953 PETERS 2,635,975

METHOD OF BONDING POLYETHYLENE To VULCANIZED RUBBER AND ARTICLE PRODUCED THEREBY Filed Feb. 27, 1951 VVE/V70@ By H. PETERS @JM @QM ATTQRH/Q/ MEW Qxk MUGS Patented Apr. 21, 1953 METHOD OF BONDING POLYETHYLENE TO VULCANIZED RUBBER AND ARTICLE PRO- DUCED THEREBY Henry Peters, Summit, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application February 27, 1951, Serial No. 212,998

19 Claims. 1

This invention relates to methods of bonding polyethylene bodies to bodies of natural or synthetic rubber and to bonded articles so produced. The invention also relates to methods of bonding polyethylene bodies to metal bodies by means oi intermediate bodies of natural or synthetic rubber and to bonded articles so produced.

The mechanical and electrical properties of the solid polymers of ethylene, referred to as polyethylene, have led to their Widespread use for electrical insulation and protective coverings in wires and cable and for numerous other purposes. It is often desirable, particularly in these electrical uses, to form a strong physical bond between the polyethylene and a rubber, natural or syntheticy as when a splice is made between a polyethylene insulated or sheathed cable and a rubber insulated or jacketed cable. However, up to the time of the present invention, no means has been available to form such a bond since polyethylene will not form a strong bond directly to any of the rubbers.

Similarly, polyethylene will not form a strong and permanent bond to metal bodies. Such a bond is often required in the termination of polyethylene insulated or sheathed cable or in other structures.

The present invention represents a solution to both these problems. The bonding of polyethylene to any of the rubbers is accomplished, according to the present invention, by the use of special techniques applied to one or more intermediate layers or bodies of polyethylene-rubber mixtures.

The insertion, between the polyethylene and the rubber, of a single layer containing only a mixture of polyethylene and rubber will not lead to the formation of a strong or permanent bond regardless of the proportions of polyethylene and rubber in the mixture. It has been found, however, that the addition of an acid carbon black to the mixture in the proper manner will cause the formation of a strong, permanent bond upon heating. This use of an intermediate layer containing an acid carbon black constitutes the simplest and most effective technique for securing a bond according to the present invention.

However, in those instances where the bond is being formed between polyethylene and rubber used as electrical insulation directly over a conductor, the use of a bonding layer which has had its electrical resistivity reduced by the addition of carbon black may not be suitable. It has been found that, Where the carbon black is omitted, a suitable bond can be formed by using a plurality (at least three and preferably at least four) of 2 intermediate layers of polyethylene-rubber mixtures of graded composition. Even when a plurality of layers of graded composition are employed, the bond can be improved by the addition of carbon black if its presence can be tolerated from an electrical standpoint.

The formation of a polyethylene to rubber bond by these techniques can be used as a means for forming a bond of polyethylene to metal since the rubber which is bonded to polyethylene can also be bonded to metal by known procedures.

An illustration of the application of the present invention to the bonding of polyethylene to rubber and, through the rubber, to metal in a submarine cable is shown in the accompanying drawing in which:

Fig. 1 is a front elevation, in section, of a portion of a submarine cable, with its outer protective coverings absenty in which polyethylene is bonded to a rubber, and through the rubber to a metal body, by means of a plurality of intermediate layers and Fig. 2 is a front elevation, in section, of a different portion of the same submarine cable in which polyethylene is bonded to a rubber, and through the rubber to a metal body, by means of a single intermediate layer containing carbon black.

These iigures show portions of a submarine cable in which vacuum tube repeaters are incorporated as a part of the submerged cable structure. The primary conductor of the cable is a centrl metal core assembly l, which is covered with an insulating layer. In the main body of the cable, this insulating layer is a cylindrical covering of polyethylene 2.

The vacuum tube repeater (not shown) is enclosed in a metal housing (not shown). It is essential that this repeater be protected from the entrance of moisture. For this reason a succession of moisture-proof barriers are provided to seal the repeater housing. To provide certain of these barriers, it is necessary to provide a strong, permanent, moisture-proof bond between the polyethylene insulation and the metal repeater housing.

The first such bond is shown in Fig. l. A cylindrical metal sleeve member 3, a portion of which is shown in Fig. 1, is fastened through intermediate metal members (not shown) te the repeater housing. A second cylindrical sleeve member 4, conveniently formed of brass, is mounted within the sleeve 3 by means of a screw thread and forms the direct bond with the cable insulation.

This bonding is accomplished by forming the cable insulation, in the vicinity of the sleeve of a covering of a rubber composition '5, in place of polyethylene. Suitable rubber compositions for bonding to brass are known in the art. typical composition is the following:

Parts by weight Crude natural rubber 100 Sulfur 3 Zinc oxide 50 Stearic acid 0.5 Mercaptobenzothiazole 0.5 Petrolatum 5 Aldol-a-naphthylarnine l The rubber covering 5 is bonded to the polyethylene covering 2 by a plurality of intermediate sections 6, l, 8, 9 formed of mixtures oi rubber and polyethylene in graded proportions. ln the bond shown in Fig. l, four intermediate bonding sections are used.

The bonding section which is contact with the rubber covering, is rnade up oi a rnixture consisting or" 6G parts of natural rubber and parts polyethylene. Section '7 is made up oi parts of natural rubber and S parts of polyethylene; section il is inade up of eil parts of natural rubber and parts oi polyethylene. Section s, which is in contact with the polyethylene covering is made up or" 3G parts of natural rubber and 'l0 parts of polyethylene.

When the rubber composition is vulcanized in contact with the adjacent polyethylene-rubber mixture, apparently soine oi the sulfur from the rubber composition into the surface oi the mixture and causes the formation of a strong vulcanized bond. The intermediate sectio s bond autogenously together and to the polyethylene by the simple adhesion oi the thermoplastic ingredients with the application oi heat.

in order to insure the formation oi a good bond, the polyethylene-rubber mixture adjacent to the rubber composition should not contain less than per cent, and preferably not less than 60 per cent by weight of rubber. The polyethylenerubber mixture adjacent to the polyethylene insulating covering 2 should not contain less than 50 per cent polyethylene and'preierably not less than per cent polyethylene. lAdjacent bodies 0f polyethylene-rubber mixtures should differ from one another in content of either polyethylene or rubber by not more than l5 per cent by weight, and preferably not more than l0 per cent by weight.

At least three bodies of graded polyethylenerubber mixtures should be used between the rubber composition and the polyethylene so as to insure a good bond. Best results consistent with simplicity are obtained with four intermediate graded compositions. A larger number rnay be used if desired.

In order to secure a goodbond between the rubber composition and the adjacent polyethylenerubber mixture, it is necessary that they be vulcanized together, as in a cylindrical rnold. 'The remaining bodies of polyethylene-rubber mixture can be bonded together and to the polyethylene insulation at the saine tine or this bonding can be carried out subsequently if desired.

The bond between the rubber composition and the sleeve il is best formed after the rubber cornposition has been partially vulcanized to a state in which it will maintain its shape. To accomplish this, the unvulcanized rubber composition is placed in the mold together with the adjacent .and the brass sleeve by a single vulcani 4 body of polyethylene-rubber mixture and the two compositions are heated under pressure until the rubber composition is suiliciently vulcanized so that it cannot be permanently deformed but still has a substantial residual vulcanizing capacity. En this partially vulcanized state, the rubber composition can more readily be inserted in the brass sleeve After its insertion in the sleeve, it can be subjected to complete vulcanization and during this procedure it becomes firmly bonded to the inner surface oi the sleeve.

With the rubber composition described above, the partial vulcanization can be accomplished by heating` at about 290 for about ten minutes. liter the partially vulcanized composition nas been inserted in the brass sleeve, the vulcanization can be cc oleted by heating at about 293 for an additional thirty minutes.

Alternatively, by using a proper mold, the bond can be formed between the rubber composition ng step, with the co position being inserted. into the sleeve 'n the unvulcanized state. The composition is then Lely vulcanized, forming a bond with both the brass sleeve and the adjacent polyethylene-rubber mixture.

The addition or" carbon black or" the propel' type, and in the proper 'n.anner, to tne polyibber mixture adacent to the rubber cornposit i will increase the range ci rubber to polyethylene ratio which can be used in the mixture and sti give a satisfactory bond. The presence or carbon black in a polyethylene-rubber mixture .uraltes it possible to forni a bond with a vulcanizable rubber composition when the rubber content of the mixture is as low as 3i) per cent by weight oi the total polyethylene and rub er.

Thus, where carbon black is not objectionable ironi an electrical standpoint, can be added to Vall ol the intermediate polyethylene-rubber mixtures or to only the polyethylene-rubber body which is adjacent to the vulcanizable rubber coinposition since tbe amount of rubber required in the latter polyethylene-rubber mixture is reduced, it is possible, where desired, to secure a satisfactory bond using only two, or only one, intermediate bonding compositions between the polyethylene body and the vulcanizable rubber body.

Such a bond formed with a single intermediate layer oi a polyethylene-rubber mixture containing carbon black is shown in Fig-2. The section of cable shown in 2 shows the second seal between the polyethylene insulation and an element which is in turn sealed to the repeater housing referred to above.

Referring back to l, the outer sleeve 3, which is fastened` to the repeater housing, is also bonded, as by brasil g, to a cylindrical copper core tube iii surrounding the insulatingr coverings 2, E, l, 8 and S. This core tube provides mechanical protection to relieve the stress on the repeater and also, by increasing the path 'which must be raveled by any inoistine penetrat- Parts by weight O Neoprene (polychloroprene) 10 Magnesium oxide 4 Dixie clay 40 Zinc oxide 30 Dibutyl ammonium oleate 2 Furnace carbon black 2 Cottonseed oil 2 Vulcanized vegetable oil Phenyl naphthylamine 2 Beyond the end of the core tube I0, the polyethylene insulating layer 2 is surrounded by a cylindrical tube made up of a neoprene section I3 bonded to a polyethylene section I4 by means of a single intermediate section I5 of a polyethylene-neoprene mixture containing carbon black.

The neoprene section I3 may be formed of any conventional neoprene composition of which a typical example is the neoprene compound given above for the sleeve I I.

The neoprene section I3 has an end portion l'I which is of larger internal diameter than the remainder of the section and which slips over and snugly ts the narrowed end I2 of the neoprene sleeve II. The neoprene section I3 may desirably have a length of the order of fifteen times its internal diameter.

The composite cylindrical tube is formed, prior to being slipped over the polyethylene insulating covering 2, by placing in a suitable cylindrical mold a portion of polyethylene tubing and an appropriate amount of an unvulcanized neoprene composition, such as that given above, with a suitable amount of a polyethylene-neoprene-carbon black mixture between the two. The mass is then heated to a temperature sufficient to vulcanize the neoprene composition, so as to form the fully vulcanized neoprene section I3, which is rmly bonded by a vulcanized bond to the intermediate bonding section I5, which is in turn firmly bonded to the polyethylene section I4.

Best results are obtained when the intermediate bonding composition consists of 60 parts by weight of polyethylene, 40 parts by weight of neoprene and l0 parts by weight of carbon block. A good bond can be obtained with neoprene contents between 20 per cent and 50 per cent by weight of the total polyethylene and neoprene. Good bonds can be obtained when the carbon black is present in amounts between 3 per cent and 50 per cent, and preferably between 5 Der cent and 20 per cent, by weight of the total polyethylene and neoprene.

As indicated, the beneficial effects of the carbon black in the bonding composition can be obtained only with the proper carbon black and with the proper compounding of the composition. It has been found that only those carbon blacks which impart an acid pH to water in which they are leached are capable of improving the bond between the vulcanizable rubber composition and the bonding mixture. In general, impingement blacks or carbon blacks which are produced by the impingement of a burning hydrocarbon gas or vapor on a surface are acid carbon blacks. Such carbon blacks are commonly referred to as channel blacks.

Carbon blacks which are produced by the cracking or combustion of hydrocarbons in free space, the so-called furnace blacks or thermal blacks, do not improve the bonding power of the polyethylene-rubber mixtures. y

Although improvement in bonding is obtained with acid carbon blacks regardless of their particle size, the improvement in bonding increases as the particle size of the black decreases. Thus, substantial improvement in bonding is obtained by the addition of a channel black having an average particle diameter of 30 to 35 millimicrons; greater improvement is obtained with a channel black having an average particle size of l0 to 20 millimicrons; and far superior improvement is obtained with a channel blaclr having an average particle size of about 5 millimicrons.

The improvement in bonding due to the presence of carbon black is not obtained if the black is milled into the neoprene or other rubber before it comes into contact with the polyethylene. The full benecial effect of the carbon black is obtained if the black is thoroughly milled into the polyethylene and the polyethylene-carbon black mixture is then mixed with the rubber. A part of the benecial effect is obtained if the black is milled into a mixture of polyethylene and the rubber. The effect is completely lost if the black is rst milled into the rubber and the rubber-carbon black mixture is then mixed with the polyethylene.

Referring again to Fig. 2, beyond the composite tube I3, I4, I5, a sleeve I6 of polyethylene surrounds the polyethylene insulating layer 2 and is heat bonded thereto. In forming the seal, the composite tube is slipped along the outside of the polyethylene insulating layer 2 until the edge of the section I4 is in contact with the polyethylene sleeve IS. The core tube i0, surrounded by the neoprene sleeve II is then slipped along the cable until the narrowed end I2 of the sleeve is completely within the end portion I 1 of the neoprene section I3 of the composite tube. The polyethylene section I4 is then bonded to the polyethylene sleeve I6 and to the polyethylene insulating layer 2 by the application of heat. At the same time, the polyethylene sleeve I6 is heat bonded to the insulating laver 2.

The end portion I'I of the neoprene section I3 is bonded to the narrowed end-I2 of the sleeve I I by rolling back the end portion I'I over the section I3, applying a low temperature vulcanizing neoprene cement to the outer surface of the narrowed end I2, rolling the end portion Il to its original position in contact with the narrowed end I2 and heating the assembly until a vulcanized bond is formed between the outer surface of the lnarrowed end I2 and the inner surface of the end portion I'I.

In the complete seal, the copper core tube I0 is bonded to the neoprene sleeve I I by vulcanization; the neoprene sleeve I I is bonded to the neoprene section I3 by a vulcanized neoprene cement; the neoprene section I3 is bonded to the polyethylene section I4 by the intermediate polyethylene-neoprene-carbon black bonding composition I5; and the polyethylene section I4 is heat bonded to the polyethylene insulating layer 2.

accusava In the description above, the polyethylene-torubber bond without carbon black has been described as carried out with natural rubber and the bond using carbon bla-ck has been described as carried out with neoprene. However, either type of bond can be accomplished with any vulcanizable natural or synthetic rubber, such as neoprene, butadiene 1,3-styrene copolymer rubber, r butadiene 1,3-acryionitrile copolymer rubber. Although it is preferable that the rubber used in the polyethylene-rubber bonding compositions, with or without carbon black, be the same as the rubber used in the rubber composition being bonded, this is not essential. Satisfactory bonds to any vulcanizable rubber composition can be obtained using any rubber in the bonding mixture.

The invention has been described above in terms of its specific embodiments and, since certain modifications and equivalents may be apparent to those skilled in the art, this description is intended to be illustrative of but not necessarily to constitute a limitation upon the scope of the invention.

What is claimed is:

l. A body of polyethylene bonded to a body of a vulcanized rubber composition by means of at least one intermediate layer of a mixture or polyethylene and a rubber containino' an acid carbon black.

2. An article comprising a body a vulcanized rubber composition and a body of polyethylene spaced from one another by at least one body of a bonding mixture containing a rubber, polyethylene and at least 3 per cent of an acid carbon black based on the tota-l weight of rubber and polyethylene, said bonding mixture having been prepared by a mixing procedure in which the carbon black is not mixed with the rubber prior to its mixture with the polyethylene, the rubber body being vulcanized to the body oi bonding mixture adjacent to it, the polyethylene being autogenously heat bonded to the body or" bonding mixture adjacent to it, the body of bonding mixture adjacent to the vulcanized rubber body containing a rubber in an amount of at least Bil per cent by weight of the rubber and polyethylene present, the body or bonding mixture adjacent to the polyethylene body containing polyethylene in amount of at least 50 per cent by weight oi the rubber and polyethylene present.

3. An article comprising a body of a vulcanized rubber composition and a body ci polyethylene spaced from one another by at least three successive, contacting, bonding layers each of which is formed of a mixture of polyethylene, rubber and up to 50 per cent of an acid carbon black; based on the combined weight of the polyethylene and rubber present, said mixture having been formed by a mixing procedure in which the carbon black is not mixed with the rubber prior to its mixture with the polyethylene, the rubber composition being vulcanized to the bonding layer adjacent to it, the body of polyethylene and each of the bonding layers being autogenously heat bonded to the bonding layers adjacent to it, the bonding layer adjacent to the vulcanized rubber vbody containing a rubber in an amount of at Vpolyethylene and rubber, each of the bonding layers having a polyethylene content and a rubber content which differs by not more than 15 per cent from that of any layer to which it is directly bonded.

4i. An article comprising a body of a vulcanized rubber composition and a body or polyethylene spaced from one another by at least three successive, contacting, bonding layers each of which is formed or" a mixture comprising polyethylene and a rubber, the rubber composition being vulcanized. to the `bonding layer adjacent to it, the body of polyethylene and each of the bonding layers being autogenously heat bonded to the bonding layers adjacent to it, the bonding layer adjacent to the vulcanized rubber body containing a rubber in an amount or" at least 55 per cent by weight oi the polyethylene and rubber present, the bonding layer adjacent to the polyethylene body containing polyethylene in an amount of at least 50 per cent by weight of the polyethylene and rubber present, each of the bonding layers having a polyethylene 4content and a rubber content which differs by not more than 15 per cent from that or" any layer to which it is directly bonded.

5. An article as deiined in claim i wherein each of the bonding layers is formed of a mixture consisting of polyethylene and a rubber containing between 3 per cent and per cent of an acid carbon black based on the combined weight of the polyethylene and rubber, said mixture having been prepared by a mixing procedure in which the carbon black is mixed with the polyethylene before it is mixed with the rubber.

An article as deiined in claim e wherein each of the bonding layers is formed or" a mixture consisting of polyethylene and a rubber.

'7. An article comprising a body ci a natural rubber composition, containing a vulcanizing agent and vulcanized to a first bonding layer consisting of 5G per cent by weight oi natural rubber and i0 per cent by weight oi polyethylene, which first bonding layer is autogenously heat bonded to a second bonding layer consisting or" equal parts by weight of natural rubber and polyethylene, which second bonding layer is autogenously heat bonded to a third bonding layer consisting of ed per cent by weight of natural rubber and 60 per cent by weight of polyethylene, which third bonding layer is autogenously heat bonded to a fourth bonding layer consisting of 3G per cent by weight of natural rubber and '70 per cent by weight of polyethylene, which fourth bonding layer is autogenousiy heat bonded to a body of polyethylene.

8. An article comprising a body oi a vulcanized rubber composition and a body oi polyethylene bonded together by an intermediate body made up of a bonding composition comprising polyethylene, a rubber, and an acid carbon black', the rubber being present in said bonding cornposition in an amount between 3G per cent and 5G per cent of the combined weight of the rubber and polyethylene, the carbon black being present in an amount between 3 per cent and 50 per cent oi the combined weight of the rubber and polyethylene in said bonding composition, said bonding composition being one prepared by a mixing procedure in which the carbon black is intimately mixed with the polyethylene before the rubber is added to the mixture, said bonding composition being bonded to said vulcanized rubber composition by a vulcanized bond and being heat bonded to said body oi polyethylene.

9. An article as described in claim 8 wherein the bonding composition consists of polyethylene, between 50 per cent and 70 per cent of a rubber based on the combined weight of rubber and polyethylene in the composition, and carbon black in an amount between per cent and 20 per cent based on the combined weight of rubber and polyethylene.

10. An article as described in claim 9 wherein the amount of carbon black in the bonding composition is about 10 per cent by weight of the combined polyethylene and rubber.

11. An article as described in claim 10 where-- in the vulcanized rubber composition is a vulcanized neoprene composition, the rubber in the bonding composition is neoprene which is present in an amount of 40 per cent of the combined weight of neoprene and polyethylene, and the particle size of the carbon black is of the order of 5 millimicrons.

12. An article containing a strong, permanent, Water-resistant seal between a polyethylene body and a metal body, said article comprising said metal body and said polyethylene body positioned in spaced relationship, a body of vulcanized rubber composition vulcanized to said metal body, at least three successive, contacting, bonding layers positioned between said vulcanized rubber body and said polyethylene body, each of said bonding layers consisting of polyethylene and a rubber, the vulcanized rubber body being vulcanized to the bonding layer adjacent to it, the polyethylene body and each of the bonding layers being heat bonded to the bonding layers adjacent to it, the bonding layer adjacent to the vulcanized rubber body containing a rubber in an amount of at least 55 per cent by weight, the bonding layer adjacent to the polyethylene body containing polyethylene in an amount of at least 50 per cent by weight, each of the bonding layers having a polyethylene content and a rubber content which differs by not more than per cent from that of any other layer to which it is directly bonded.

13. An article as described in claim 12 wherein the metal body is formed of brass, wherein the rubber in the vulcanized rubber body and in the bonding layers is natural rubber and wherein there are four bonding layers disposed between the vulcanized rubber body and the polyethylene body, the rst layer adjacent to the vulcanized rubber body being formed of 60 per cent by weight of natural rubber and e() per cent by weight of polyethylene, the second layer adjacent to the rst layer being formed of equal parts by weight of natural rubber and polyethylene, `the third layer adjacent to the second layer being formed of 40 per cent by weight of natural rubber and 60 per cent by weight of polyethylene, and the fourth layer disposed between the third layer and the polyethylene body being formed of 30 per cent by weight of natural rubber and '70 per cent by weight of polyethylene.

14. An article containing a strong, permanent water-resistant seal between a polyethylene body and a metal body, said article comprising said metal body and said polyethylene body positioned in spaced relationship, a body of a vulcanized rubber composition vulcanized to said metal body, a body of a bonding composition positioned between said vulcanized rubber body and said polyethylene body, said bonding composition comprising polyethylene, a rubber in an amount between 30 per cent and 50 per cent of the combined weight of the polyethylene and rubber, and an acid carbon black in an amount between per cent and 50 per cent of the combined weight of the polyethylene and rubber, said bonding composition being one prepared by a mixing procedure in which the carbon black is intimately mixed with the polyethylene before the rubber is added to the mixture, said body of bonding composition being bonded to said vulcanized rubber body by a vulcanized bond and being heat bonded to said polyethylene body.

15. An article as described in claim 14 wherein the metal body is formed of copper, wherein the rubber in the vulcanized rubber body and in the bonding composition is neoprene, and wherein the bonding composition consists of sixty parts by weight of polyethylene, forty parts by weight of neoprene and ten parts by weight of channel black having an average particle size of the order of 5 millimicrons.

16. The method of forming a strong, permanent, water-resistant seal between a vulcanized rubber body and a polyethylene body comprising bringing a body of a rubber composition containing a vulcanizing agent into contact with a first body of a bonding composition consisting or polyethylene and at least 55 per cent by weight of a rubber, vulcanizing said rubber body in oontact with said bonding composition, placing at least two additional bodies of a bonding composition in successive arrangement between said rst body of bonding composition and a polyethylene body, all of said bonding compositions consisting of polyethylene and rubber, the composition adjacent to said polyethylene body containing at least 50 per cent by weight of polyethylene, each of the bonding compositions havins a polyethylene and a rubber content which diifers by not more than 15 per cent from that of any other bonding composition with which it is in contact, and heat sealing the polyethylene body and the bonding compositions to each of the other bonding compositions with which it is in contact.

1'7. The method as dened in claim 16 wherein the rubber in the vulcanized rubber composition and in the bonding compositions is natural rubber, and wherein there are four bodies of bonding composition disposed between the vulcanized rubber body and the polyethylene body, the first bonding body adjacent to the vulcanized rubber body being formed of per cent by weight of natural rubber and 40 per cent by weight of polyethylene, the second body adjacent to the first body being formed of equal parts by weight of rubber and polyethylene, the third body adjacent to the second body being formed of 40 per cent by weight of rubber and 60 per cent by weight of polyethylene, and the fourth body disposed between the third body and the polyethylene body being formed of 30 per cent by weight of natural rubber and per cent by weight of polyethylene.

18. The method of forming a strong, permanent, water-resistant seal between a vulcanized rubber body and a polyethylene body comprising forming a bonding composition by intimately mixing between three and fty parts by weight of an acid carbon black with between thirty and iifty parts by weight of polyethylene and subsequently adding to the mixture between fty and seventy parts by weight of a rubber, placing a body of said bonding composition between a polyethylene body and a body of a vulcanizable rubber composition, and heating said three bodies in contact until the vulcanizable rubber composition has vulcanized and formed a vulcanized References Cied in the le ofV this patent UNITED STATES PATENTS Number' Name Date Swan et a1 Jan. 21, 1936 Kemp. et al; Nov. 28, 1939 Child' et' al Feb. 1, 1944 Cox Sept. 9, 1947 Kitchin et a1. Mar. 1, 1949 Calvert Feb. 13, 1951 Se1by' Oct. 2, 1951 Hutchins Nov. 27, 1951 

1. A BODY OF POLYETHYLENE BONDED TO A BODY OF A VULCANIZED RUBBER COMPOSITION BY MEANS OF AT LEAST ONE INTERMEDIATE LAYER OF A MIXTURE OF POLYETHYLENE AND A RUBBER CONTAINING AN ACID CARBON BLACK.
 16. THE METHOD OF FORMING A STRONG, PERMANENT, WATER-RESISTANT SEAL BETWEEN A VULCANIZED RUBBER BODY AND A POLYETHYLENE BODY COMPRISING BRINGING A BODY OF A RUBBER COMPOSITION CONTAINING A VULCANIZING AGENT INTO CONTACT WITH A FIRST BODY OF A BONDING COMPOSITION CONSISTING OF POLYETHYLENE AND AT LEAST 55 PER CENT BY WEIGHT OF A RUBBER, VULCANIZING SAID RUBBER BODY IN CONTACT WITH SAID BONDING COMPOSITION, PLACING AT LEAST TWO ADDITIONAL BODIES OF A BONDING COMPOSITION IN SUCCESSIVE ARRANGEMENT BETWEEN SAID FIRST BODY OF BONDING COMPOSITION AND A POLYETHYLENE BODY, ALL OF SAID BONDING COMPOSITIONS CONSISTING OF POLYETHYLENE AND RUBBER, THE COMPOSITION ADJACENT TO SAID POLYETHYLENE BODY CONTAINING AT LEAST 50 PER CENT BY WEIGHT OF POLYETHYLENE, EACH OF THE BONDING COMPOSITIONS HAVING A POLYEHTYLENE AND A RUBBER CONTENT WHICH DIFFERS BY NOT MORE THAN 15 PER CENT FROM THAT OF ANY OTHER BONDING COMPOSITION WITH WHICH IT IS IN CONTACT, AND HEAT SEALING THE POLYETHYLENE BODY AND THE BONDING COMPOSITIONS TO EACH OF THE OTHER BONDING COMPOSITIONS WITH WHICH IT IS IN CONTACT. 